Interesting paper.  The section "Initial assessment of the system’s long-term stability" says they think it *should* be unstable over long timescales.  One of their statistical analyses gave 8% chance of stability over 1 billion years.  But the fact that it is there implies there may be other factors stabilizing the system.

Seems like a job for the IISS - if only we could just jump over and investigate...

On Thu, Feb 23, 2017 at 2:08 PM, C. Berry <xxxxxx@gmail.com> wrote:

Oh, my, resonances indeed! Just eyeballing it:

b:e:f:g 1:4:6:8

d:e 2:3

None exact, but all close enough to create resonance effects. It's interesting that c doesn't seem to resonate with anything.

On Thu, Feb 23, 2017 at 8:03 AM, Bruce Johnson <xxxxxx@pharmacy.arizona.edu> wrote:

> On Feb 23, 2017, at 8:57 AM, Bruce Johnson <xxxxxx@Pharmacy.Arizona.EDU> wrote:
>
>>
>> On Feb 23, 2017, at 7:34 AM, C. Berry <xxxxxx@gmail.com> wrote:
>>
>> Ah, yes. The Traveller version of "A wizard did it." :)
>>
>> Has anybody seen the orbital periods for these planets published? It would be easy to look for resonances. I'd be surprised if there's room for everything to have small integer resonances in a 7-planet system that small, but I've been surprised before.
>
> Here’s the article they published in Nature, haven’t read it yet, but that info might be in there: http://dbdev2.pharmacy.arizona.edu/miscjunk/nature21360.pdf
>

And to answer my own post, yes Table 1 lists them, some with astonishing precisison.TRAPPIST-1b has a period of 1.51087081±0.60×10−6 days. That’s 0.05 seconds of variance!

Which if these weren’t actual rocket surgeons I would classify as ‘because my calculator said so’ kind of numbers :-)

--
Bruce Johnson
University of Arizona
College of Pharmacy
Information Technology Group

Institutions do not have opinions, merely customs


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